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MG Midget and Sprite Technical - MGB Dampers ... again

So I've decide to do this. Bought the plates from Mamba which also come with a whole host of bits including Nylatron bushes which I think will be much too hard for a road going Sprite (unless you know different).

This is for an Austin Sprite re-build which I should be able to start soon. Not sure how long it will take but I retire in 2 years time and I want it finished by then!!

I've spent a good few hours searching the archives for this and out of the many I found there are a couple of threads where it is said the trunnion should be rotated 180 degrees. Not sure why this should be? Anyone any idea?

If the trunnion is turned round it adds 3 cm to the length of the shocker arm, which can't be a good thing.
The MGB arm is 205mm and the midget arm is 185mm. The sliding attachments make it easy to set the camber and there are a selection of washers used to adjust the castor.

The Mamba plates seem to be well made. They are infact 2 plates welded together which makes the laser cutting easier. The adjustable bits are hex head bolts with the head thickness reduced. Plate attachments are 3 CS screws into the standard holes.

The rubber buffer on the Midget is in line with one of the pads on the MGB shocker arm for full droop control. Not sure if I should add another to go under the one on the other arm? What do you think?

Pictures when I can get into the garage.

Rob








Rob aka MG Moneypit

hi rob
i have the same and hope to start work after xmas,
i look forward to hearing how you get on.
It certainly seems to be a well made kit of parts.
I think 'mr mamba' uses his kit for race/track hence the poly bushes
rgds tony
tony boyle

Rob. I thought you were rebuilding the Austin Sprite to original Austin Sprite spec. MGB dampers???

Have you got the dampers for your kit? I will be very interested to see the outcome. It's something I've been thinking about doing on my own Sprite, but I bottled it😔.

If you wouldn't mind bringing the plates to the next meeting, I'd very much like to see them.
Bernie Higginson

Original but with subtle upgrades!!!!

OK, I'll bring them. See you there if not before.

Rob
Rob aka MG Moneypit

hi
i had a long chat with mamba before i bought them with some good advice...Thoroughly wash out your b shocks, new standard valve if required and new oil. This can vary as to what you intend to do with the car, Mamba will give you advice on the viscosity oil needed
Rgds tony
tony boyle

Old postings about MGB and A60 dampers in a Midget mention turning the trunnions 180 degrees. Mamba never mentioned this so it's not necessary. I just wondered why these posts mention it. Any ideas?

Rob
Rob aka MG Moneypit

Also very interested in this as some may have seen I'm having front suspension issues... I virtually ordered some but they weren't in stock and by the time they were, many other things had cropped up and could no longer afford!

I don't remember reading about rotating trunnions, and mamba didn't say to to me either.

Might try and make the next Cheshire meet if it's not too far away and I'm not working!
Karl Bielby

Back in the day with MGB or A60 dampers using one of the original mounts the trunnion has to be rotated to create a nominal zero degrees camber - with the introduction of sliding plates the damper position moves inboard and the camber angle becomes adjustable, so the trunnion no longer needs to be turned. However with sliding plates you would need to borrow or make an angleometer to set up the camber at normal suspension deflection. Not sure you can adjust the caster - the basic geometry and suspension articulation is set by the position and angle of the wishbone bushes, so all you can do is 'correct' it to the factory spec.
Fergus

Mamba supply a number of washers that are used to make up the distance between the arms on an MGB damper. This distance is wider than the trunnion. They provide quite a few washers and suggest that changing the positions of the washers will provide some Castor correction. eg, if you need 4 washers to make up the distance you can do 2 each side or one before and 3 after or 3 before and 1 after etc. Ultimately it does depend on your lower wishbone but in the event of wishbone/kingpin and damper not quite lining up you have some adjustment.

Must take some pictures!!

Rob
Rob aka MG Moneypit

Yes, exactly that. The washers are for correcting the fore/aft position if the trunnion to match the articulation of the kingpin. Ultimately caster should be around 3 degrees positive.
Fergus

Rob
If it is not impolite to ask - how much are the Mamba plates? Their website does not give a price but says they are "less than you think"!
Chris Hasluck

The whole kit and kaboodle was £130.

Rob
Rob aka MG Moneypit

I had time to try the plates and dampers on one side.
This photo shows I've cut a little bit of the inner wing away, (back to where the inner part has a flange into the engine bay) but clearly not enough. The Mamba website shows quite a lot of inner wing cut away but I don't think it needs to be that severe. I would like to determine the minimum I can get away with before going further.

Rob


Rob aka MG Moneypit

This photo shows the view from within the engine bay. The position is about where it needs to be to give about the same camber as the original. There isn't much adjustment left to give any more positive camber, but lots for more negative.

The pad on the front arm is directly over where the bump stop would be. I wonder whether I needs to put another under the other arms pad.

The nuts are not the proper ones.

Rob


Rob aka MG Moneypit

This last photo shows the view from the front.

So far I have noted that the plate needs to have the corners more rounded. It's got a 45 degree cut on the corner but it needs to be 60 degrees because with more negative camber on full droop the arms can touch the baseplate. I'll know more as I get on with it.

Rob


Rob aka MG Moneypit

They look really good. Something I'm still definitely keen to do. Do you think that with a bump stop fitted,it would stop the arm contacting the plate?
Karl Bielby

forgive the question form a bloke who doesn't know, but whats the idea behind this mod ?
It looks very business like, but I am keen to hear what the advantages are.
P Bentley

It's to provide triangulation of the top suspension arm and the ability to change the camber on the front suspension. The standard damper has a single articulated arm which puts a lot of strain on the bearings in the damper. A lot of problems with reconditioned arms involves this bearing and other things as well.

Using MGB dampers provides this triangulation with less likelyhood that the bearings will be compromised (but it does leave other problems common to all lever dampers when reconditioned).

There is a mod which can add another arm to do this with the standard damper which can be purchased from Peter May and probably others. There is information in the archive and on the web in general about how to do it yourself.

Rob
Rob aka MG Moneypit

Not just bearing issues with the original dampers; it's possible to get quite a bit of arm flex too under braking. This helps prematurely wear the bottom pin out.
Rob Armstrong

hi rob
have you got any further with the issue of the lever arms fouling the plate on full deflection.
after seeing your initial post i decided it was time to fit mine but i decided to follow your fitting to see any problems arose.
I have looked at the problem and it looks that with the bump stops in place it should be ok. Any thoughts

rgds tony
tony boyle

I didn't get any time in the garage this weekend and this week looks doubtfull due to xmas commitments. May have to wait for this weekend.

I think you are correct that with the bumpstop fitted there is little chance of it contacting the base plate.

I see that the MGB has a bolt on dual bump stop. I may look into seeing if this can be made to fit a Midget.

Rob
Rob aka MG Moneypit

hi rob
as you said in your first post it should be easily possible to fit the second bump stop..just needs a 1/2 inch hole drilling...almost looks like the chassis was originally designed for a double arm shock
rgds tony
tony boyle

hi rob
just wondering how far you have got fitting the b shocks
I am just finishing off a couple of other jobs and then start the shocks
rgds tony
tony boyle

Now that xmas and new year is over and done with, I got an hour in the garage tonight, after a day at work. I cut a bit more out of the inside wing to clear the shock arm. The inner wing towards the front of the car will also need a bit of trimming but I should be able to retain the two fixings for the front splash shields and radiator support.
In the attached image it appears that the left hand arm is touching the inner wing but it isn't. It's just the camera angle.

Rob



MG Moneypit

The view from the front showing arm and bump stop relationship. The shock is in the approximate position to give standard camber.


MG Moneypit

From inside the engine bay.

I still think I will have to trim the baseplate a tad. There is enough jiggle room with the way the shock is mounted on the baseplate that I can get the arm to miss the baseplate on full droop. I don't think I will be able to know for sure until the rest of the suspension is fitted and I can work out how much packing is needed on either side of the Midget trunion.

Rob


MG Moneypit

hi rob
spent some time in the garage today. Set up the o/s shock.
On max down stroke against the buffers-plural, the arms JUST clear the mamber plate. It is tight but i think if you drove with 5 degrees neg cam it might hit. I was going to set up 1.5 degrees and that looks good. Re the caster angle/spacers
, i marked with a template where the trunion was on the midget shock and will set it up as before...should be fine
Rgds tony
tony boyle

Looks like you have overtaken me. Must pull my finger out. Have you any photo's? How much of the inner wing did you remove?

Rob
MG Moneypit

Looking really good, this is definitely bringing me round to the idea. Just going to wait for the verdict once driven!

On the buffer front... Does it matter that they contact on full extension? I can't imagine that they will contact in driving..? Only when jacked and weight off?

I could be wrong!
Karl Bielby

hi all
busy tomorrow. Will try some snaps on saturday.
I think without the bumps the levers would just foul the plates. Worth fitting the extra one

rgds tony
tony boyle

hi guys some photos..not too bad
This on show downward movement of the arm onto the bump stops..you can just make out the clearance between the arms and the plate. This is set up at app 1./5 deg negcam
The more you increase the negcam the nearer the arms get to the plate on the downstroke


tony boyle

next pi shows innerwing cut out. No need to go up any more as the uplift of the arm is limited by the bump stop within the road spring
Still a little tidying to do !!!


tony boyle

Self indulgence

rgds tony


tony boyle

Tony, I did a bit more on mine today but the images are still on my phone. Will download tomorrow.

I made room on the inner wings for the full stroke of the MGB damper arm but realised after I did it that the MGB stroke is 9.5 ish inches and the Midget only 7.5 ish inches so probably cut out too much. Anyway, it's done now and will make the other side the same then do a bit of tidying up.

More pics tomorrow.

Rob
MG Moneypit

A quick photo off my phone. This shows the outline of the hole in the drivers side inner wing transferred to the passenger side. It could have been shorter due to differences in suspension travel as I mentioned in the last post.

Rob


MG Moneypit

good morning rob
i have finished one side apart from the brake pipe.
I spoke to Mr mamba yesterday and he gave some good advice on set up. If you want to call me for a chat i will be happy to pass on the info...evenings, 01273 833144
All is looking ok so will start the other side later this week
rgds tony
tony boyle

I have been following this subject with a vague interest but surely it relies on having a good working MGB damper [either new or reconditioned]. If someone can supply good quality MGB dampers why cant similar items be supplied for Spridgets? Just a thought....
Doug Plumb

Doug l think the point is that the MGB version has the twin lever arms so it gives better location to the top trunnion, and resists torsional twisting better. Other than that, as you say, the Midget and MGB ones are similar in operation and performance.

As a damper, the Midget one is pretty good when in good condition, and originals lasted well. The problem is in providing the top suspension arm function where the design is not so good!
Guy W

Tony, I'll keep your number on file because I don't think I will be in a position to drive the Sprite this year.

Also, the question of why use MGB dampers and do recond ones suffer the same as Midget dampers.

On a Midget damper because there is only one arm it is subject to forces not experienced by MGB dampers. Although the Midget suspension design is adequate, the fact it only has one arm does mean there is a greater risk of damage to the bearings and shaft which makes it scrap. Most re-cons of Midget dampers are little more than a clean up and black spray paint. If the fluid is checked, topped up or replaced it's a bonus. It's not feasible to do anything else at the price they sell at.

I think that the chances of getting a good MGB damper re-con are far higher than a Midget one.

Rob
MG Moneypit

How much did you pick up your B dampers for? Just trying to put together a total cost.

Where about in Cheshire are you Rob? I'm in Manchester and may be keen to have a look at some point if that would be ok??
Karl Bielby

Karl, not far from the airport using airport transfers tunbridge wells. Let me know if you want a look see but give me a chance to tidy up the garage!!!!

I've bought 2 sets of MGB dampers recently. One set was a pair of reconditioned uprated (for V8?) I got off Gumtree for £70 a pair. I also got a pair of NOS dampers off eBay a while back and think I paid not much more.

Most used MGB dampers would probably be ok with a cleanup inside and out and new fluid.

Rob
MG Moneypit

Oh ideal, I work at the airport!

Yeah I'm definitely interested in a look. Am i right in thinking that you have one side almost done?

Yeah, I was thinking that given the axle will have much more even loading, the beatings will last much longer in them. I'll keep my eye out for a set over the next few months I think.
Karl Bielby

OK, my email is my moniker (without spaces) at the email service provided by Google.

I've cut out the other side now but have removed everything but no problem to put back.

Rob
MG Moneypit

hi rob
My job finished !!!!!!I i have set up 2* neg camber.
That is almost at the end of travel on the plates. It will just go to zero then all the adjustment is back/negative.
that is fine as no one wants positive camber unless you have a hillman imp !!!
I must say it does not look any different however i am still in a cramped garage and cant stand back to see.

How are you progressing ?
rgds tony
tony boyle

Hi Tony, I'm not doing very well really. Got a right shoulder injury which is aggrevating to say the least.
I did the other inner wing with a power jigsaw which didn't help my shoulder injury much. Got an ultra-sound scan on Saturday to see what's up.

I've also been messing with brakes/discs/calipers trying things I'm sure others have tried before.

And it's bl**dy cold at the moment.

3 good reasons for not much progress.

Rob
MG Moneypit

Blimey, I've been doing this for exactly 1 year, where did the time go to?

Anyway, I'm resurrecting this thread because I'm hoping Tony Boyle or Karl Bielby will read it and to seek some advice from from the more technically minded than I.

After mucking about with big discs conversions etc. I realized that all this mucking about is just delaying the Sprite build, so I have fitted standard discs and calipers. I intend to retire this year which will mean selling up and downsizing (the house not the garage!!!) and I would rather like the Sprite to be finished, if possible.

Fitting the MGB dampers has meant that the hole in the wing for the brake hose disappeared. I have drilled a hole at about the same height as original but it is about 1 inch further back than original. The car is still on a rotisserie and the front suspension is complete so at the moment is in the full droop position. With a standard brake hose I find that on full lock (full right lock on the right hand side) the rim of the wheel just contacts the hose.

Is this serious? The only scenario I can envisage for the suspension being in this situation would be a few milli- seconds before I flip the car!!!!!

If Tony or Karl have any photos of how they positioned their brake hoses I would appreciate it.

Rob


MG Moneypit

Congrats rob

Your almost done with only 9 months to spare from (Nov 2016)

I know hard to believe how time flys especially when you loose your ambition for working on the car.

Luckily spring is just a couple months away and good weather to do my frontline suspension and big brake upgrade before the real driving season begins

Good luck with crossing the line to completion

Prop






1 Paper

Rob,
had a similar issue when rebuilding onto a Heritage shell.
IIRC there should be a small welded bracket on the bump stop mounting where the brake pipe and flexible hose meet.
It was missing on the Heritage shell so transferred it from the old shell (which luckily I hadn't got round to scrapping).
Jeremy MkIII

Jeremy, I think it depends on what year and spec the shells are built to. Early brake lines used that bracket whereas later ones just went through a hole in the inner wing.
David Smith

DS is correct. Later cars had a hole in the inner wing for the brake flexi.

I re-assembled everything again to take photos and this time there is 2mm clearance. I think I must have put some rotation on the flexi as I tightened the nut which may be a possible solution.

The attached image is trying to show the clearance as is.

Rob


MG Moneypit

The next image is side on.

I think I should take the spring out and do a proper check of all steering angles and suspension travels to make sure I haven't missed anything.
That will be my job today.

Rob


MG Moneypit

I've got a RWA Heritage shell and modern made Triumph type steering rack and the bleed nipple just touches the flexi-hose on one side but as I have a nipple cap on it it doesn't seem to wear, I only noticed because of the clean patch.
Nigel Atkins

Well I did the other side (left) and it is slightly worse in that the balance weight on the inside of the spare I used to check clearance is rubbing on the hose. I can cure this by putting a slight twist on the hose as I tighten it up.

It occurred to me that I haven't set the toe in which might effect the clearance. I'm not sure if the lock is limited by the steering rack or the kingpins.
When correct toe in is set does one kingpin reach its limit before the other?

I might just fit 3mm spacers to gain a bit of clearance. Would I need slightly longer studs on the front if I do use a spacer?

I have new studs on both hubs but they don't seem long enough. Even with standard Rostyles they don't protrude at all out of the nuts. I got them from the shop that rhymes with Toss.

Rob

MG Moneypit

Rob,
The lock is limited by two "ears" on the bottom of the kingpins. On my car, on full lock and with my 5 1/2J Cosmic wheels the tyres brushed the inner wing on full lock. I built up the kingpin ears with weld and reground flat surfaces on them with an angle grinder to give the required lock limit for tyre clearance.

As for the brake hose, adding a slight twist as you have done should just get them to tuck inwards and out of the way without adding any stress. I did that, but also fitted some SS wire coil hose protectors aquired off a scrapyard pug205.
GuyW

Thanks David,
mine's a 71 facelift model so is a couple of years earlier than Rob's which may explain the difference.
Jeremy MkIII

Rob,
Rostyle nuts are long closed type, hub cap wheels have the open nuts - or am I missing something as usual.
Nigel Atkins

hi rob
one year down the line and all is well with my conversion. I made the hole for the brake line more or less where you have it but although clearance is tight, nothing rubs. When you set the camber it needs to be under load. From my experience you should set up
by eye then, if you can, drive the car for a few hundred yards and set the camber, a bit fiddly with the car sitting on the wheels .If you set it even with stands under the wishbones, it will be different when you put the car back on the ground Must be done on flat ground..Dont forget to re-track when you are happy with the camber, Worth all the effort

rgds tony boyle
tony boyle

Nigel. I just picked out 2 wheel nuts from my box of used ones which just happened to be open ended nuts.

Tony, yes I think you are right. I probably have far too much negative camber at the moment as the damper is quite far inboard. So less would push the wheel out at the top. And of course other things like tracking set-up would help as well. Maybe I'm worrying too much. I'll put it on the back burner, get on with the build, and maybe worry about it later.

Guys trick about lock limitation is a really good idea too.

Rob
MG Moneypit

Hi Rob!

Sorry I have just seen this! By the look of it, the area I chopped out of the wing was much smaller.. it may be different on a 1500.

I cut just by the brake hose, so it hasn't moved location. The hole us not slotted, meaning that unjust need to release the jam nuts and I can slide the pipe free.

As Tony says, all well worth the effort, I was absolutely amazed at the difference (and still am!!)

I set the camber using an app on my smart phone against the wheel. Got it pretty spot on! I did find it a bit of a pain adjusting the camber as it's hard to slide the dampers with weight on, I think I got the nuts just loose enough, then I could slide the damper with a lever.

Karl
Karl Bielby

I must say the double link MGB dampers certainly look the business! Very nice. I know its not the same but it looks so much better than those frontline links.
GuyW

I like it because it looks like it was meant to be there. Doesn't look like a mod.. and the handling is superb now, like a go cart!


One thing I meant to mention, when I cut my inner wing, I felt behind and could feel another sheet of steel that felt like the exact shape I wanted. So I cut to that and it was perfect. Almost like the mgb dampers were supposed to be on there, but they changed their minds and extended one sheet to cover the enlarged hole.. will try and get pics..
Karl Bielby

hi
like Karl says difficult to fine tune the camber with the weight on, but it is a must. Re the wheel rubbing
..i have non standard wheels so the offset may be different and just clear the hose . Re the comments 'like they were meant to be there' you have to wonder if a double arm was the intention as the chassis is designed to take two bumpstops, just the hole needed drilling
rgds tony
tony boyle

That's another point Tony, I'm pretty sure there has been some previous thought into fitting them, which was then decided against for some reason.
Karl Bielby

Karl,
I've been following this thread as I am currently fitting the Mamba plates and MGB dampers to my '73 Midget. I have encountered the same problem that you had with the limited travel, having found your post in the MGB Technical section. The lever arms on the nearside damper do not extend far enough to reach either the rebounds or the trunnion.
I see from your post that you fitted another damper but did you ever establish any reason why the travel was limited in the faulty unit as I would like to understand the problem before returning for exchange.
Kind regards,
Ross
R Livingstone

Are you sure your Turions are installed correctly not 180º backwards


Just a thought
1 Paper

Ross, if one of your dampers has a different movement range than the other it could be that the arms are in the wrong position. Put the two dampers side by side and check they both go up to the same angle. If the suspect one has a greater angle fully up it could be the arms have been put on in the wrong position. One arm goes on a splined shaft, the other is just clamped. The angles can be changed by moving the arm in relation to the splined shaft.

A photo might be useful.

Rob
MG Moneypit

Rob,
I think that's the problem. Going downwards the arm bottoms out well short of the rebounds and trunnion but appears way too high at the extent of the upward travel. The operating travel in this particular damper is probably sufficient on the MGB as they are located horizontally. The Midget location being set back at an angle requires the arm to travel lower below the centreline of the damper body. As you say I will need to set the pistons to neutral and adjust the arm location to achieve the correct travel either side of this position. Probably best to set the other side to suit. Would you agree ?
Ross
R Livingstone

Ross, if they are meant for an MGB they should be identical if properly reconditioned. I've had recon MGB dampers in pairs in the past and they have been identical.

Rob
MG Moneypit

Hi Ross,

As Rob says! I had both dampers off the car and one went down way past the base, and the other only just mate it level with. I just took them back to miss and asked for them to get their entire stock out for me to check. I found two that went the farthest and took them!

Hope that helps!

Karl
Karl Bielby

Rob, Karl,
Thanks for your advice. These were bought as a reconditioned pair but obviously have been reassembled with the arms in different locations. I'm now having the shafts pressed out and replaced in the correct orientation to suit the Midget.
Thanks again,
Ross
R Livingstone

Yeah I just bought the cheapest ones in could fine, (£15 if I remember) thenntook them to moss and exchanged for reconditioned.
Karl Bielby

This thread was discussed between 24/11/2016 and 05/04/2018

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.